Using FFT (Fast Furrier Transform) and PSD (Power Spectral Density) block in Simulink

Hello Basically, I have to issues. Firstly, how can I use the output of the FFT or PSD blocks in Simulink if I want to export it to Matlab’s workspace using Simout? The results look a bit strange like a n*n*n matrix. Especially because I need the frequency of the peaks (rather than the magnitude itself) I’m just wondering how I can extract that. The second issue is to how to lively to do that on a specific segment of data one after each other. As an example, assume there is a 15 second signal. I want to a PSD on every 1 second block one after each other and get the data from it ( I don’t want to visualise that). So, is there any where to kind of chop the running time history (with or without overlap) and do the math operation (such as PSD or FFT) on that? Thanks in advance.